THURSDAY, Aug. 12 (HealthDay News) - It sounds like a great prescription, but a new study finds that many heart patients aren't all that sweet on using chocolate as medicine.

Researchers in Australia discovered that patients more often preferred boring pills over antioxidant-rich chocolate to help control their blood pressure.

"Fifty grams of dark chocolate [roughly one average-sized candy bar] containing 70% of cocoa daily was less acceptable than a pill of tomato extract or placebo," said Karin Ried, co-author of a letter appearing Aug. 12 in the BMJ.

So, because patients didn't stick with the regimen, "chocolate might not be practical to be recommended as long-term treatment for blood pressure," she added. "However, eating chocolate occasionally or regularly might have health-benefiting properties."

Several trials have found that the antioxidants in dark chocolate can help lower blood pressure, including one that found that even 30 calories of chocolate a day could help (a little more than a Hershey's Kiss).

"We know that flavonoids and polyphenols [both antioxidants] have been able to decrease blood pressure, so we've said that having a square of chocolate that's 70% cocoa [could be] part of a healthy diet," said Dr. Suzanne Steinbaum, a preventive cardiologist with Lenox Hill Hospital in New York City.

In the new trial, originally published in 2009, Ried and colleagues randomized 36 people to receive 50 milligrams of "commercially available" dark chocolate (70% cocoa and 750 milligrams of polyphenols), a tomato extract capsule (with 15 milligrams of the antioxidant lycopene), or a placebo daily for eight weeks.

The tomato extract contained levels of antioxidants "equivalent to four or five medium-size tomatoes," Ried said, while the placebo capsules "contained mainly soy oil."

Although the dark chocolate did have a more salutary effect on blood pressure than either the tomato extract or the placebo, many participants just didn't find this treat palatable.

About half of those in the chocolate group "found it hard" to eat this amount of chocolate every day, while 20% "considered it an unacceptable long-term treatment option."

Participants had no problem with a daily pill, however.

The findings seem counterintuitive to the growing waistlines seen around the world, but Ried thinks she may have a reason for the reactions.

"There is something about consuming a food item voluntarily or having to eat it on a daily basis over a period of 12 weeks," she said. "In particular, half a block of dark chocolate [50 grams] is not an insignificant amount. Participants in our trial reported strong taste and concerns about fat/sugar content as reasons for unacceptability of chocolate as a long-term treatment option."

Or there may be other reasons and other options.

"I can't eat just 30 calories of chocolate, personally," said Marianne Grant, a registered dietician and certified diabetes educator at Texas A&M Health Science Center Coastal Bend Health Education Center, in Corpus Christi. "This does highlight the effect of antioxidants. Maybe if we could put them in other things, that might be better."

"This is another study that says dark chocolate is helpful in reducing blood pressure but really shouldn't be considered a medication," Steinbaum concluded.